Exotic Aedes mosquito species are commonly found in Darwin as larvae in receptacles that hold or have held water on vessels or cargo from overseas. Aedes aegypti could also be found in receptacles from north Queensland and transported to other States and regions of Australia. Aedes species eggs are desiccation resistant and can often be present in either water holding or dry receptacles. Procedures approved to treat receptacles and cargo include the application of methoprene or residual pyrethroid insecticides sprayed to the interior of dry or water containing receptacles in order to kill larvae or eggs. Fumigation with methyl bromide is applied to larger or difficult to treat receptacles. Chlorination is used for the treatment of receptacles where the utilization of the receptacles does not allow for insecticide treatment, eg. drinking water receptacles, or where the surface treatment poses insecticide residue concern. These treatments are part of routine quarantine inspection and control procedures in the 400 m quarantine zone around air and seaports (National Arbovirus Advisory Committee, in prep.). There have been some questions on the amount of chlorine for the treatment of various receptacles.
The present guidelines are recommendations for chlorination procedures to treat receptacles containing or being likely to contain larvae and/or eggs for quarantine purposes. They should be read in conjunction with the document “Recommended protocol for action when a ‘risk importation’ or introduced exotic mosquito is detected"